Depends on your budget and if you are talking squirrel heads or something larger. I like a low power variable on most of my 22's. 3-9 or 2-7. I would recommend Burris, or Vortex.
vortexoptics.com The prices on the website are a little higher than most retailers actual price.
burrisoptics.com My preference is vortex, and for a 22 start at the Diamondback line. Have fun deciding, there are lots of excellent scopes on the market.